Both Brown and Darling are referring to Cameron's plans to scrap Labour's NI increases as 'taking money out of the economy'.
Ah, I see. For Statists, there is only one economy - the fantasy model, the make-believe, away-with-the-fairies command economy under the direction of the central State. For Brown and Darling, the State and the Economy are one - so depriving the State of additional taxes is 'taking money out of the economy'
In the real world, of course, not implementing the NI increase will maintain and encourage employment and the additional money retained in the real economy will multiply its impact. In the real world, 'taking money out of the economy' means allowing Labour to increase taxes and squander the product on non-productive ends.